Integrated circuits currently are manufactured in compact packages including thousands, and even millions, of transistors and other components fabricated on semi-conductor wafers, connected to lead frames and potted in packages from which a large number of leads extend. Large scale integrated circuits and very large scale integrated circuits (LSI and VLSI circuits) result in complete electronic systems or major parts of complex electronic systems, all packaged in relatively small-sized integrated circuit packages. These circuit packages sometimes are used alone as the electronic "heart" of a system or device, or are interconnected together as part of a larger system in which more than one LSI or VLSI integrated circuits are used.
It is very important for integrated circuits to operate properly for their intended purposes once they are shipped from the manufacturing facility, since, if such circuits are incorporated into other devices, failure of the circuit to properly function could result in the failure of a much more expensive device or system into which the circuits are incorporated. It has been found, that if an LSI circuit or VLSI circuit is defective in some way which may cause it to fail, the failure usually occurs within the initial hours of operation. Once some pre-established minimum number of hours of proper operation takes place, the circuit typically does not fail; unless of course it is subjected to some type of catastrophic surge voltage, or the like.
In order to ensure that integrated circuit packages, which are shipped to customers for incorporation into finished products, will operate properly in those finished products, it is a common practice to operate the finished, packaged integrated circuits for a period of time under power. This is done to cause any failures which are likely to occur to occur before the integrated circuit packages are shipped. To do this, several integrated circuit packages are interconnected into receptacles on relatively large "burn-in" printed circuit boards, which have printed circuit interconnections going to each of the receptacles for each of the integrated circuits to be operated on the board. The circuit leads for each of the different receptacles extend to one edge of the board, where they terminate in a connector block having a large number of pin connectors extending from it. The different pin connectors each are connected to different ones of the printed circuit leads, connected to the sockets for the different integrated circuits to undergo test.
Burn-in boards can have hundreds of connector pins on the connector block. These pins are physically aligned with a corresponding group of pin receptacles on the front of a tester, which then provides the operating power and signals to the pins in accordance with the devices undergoing test. Thus, to effect a "burn-in" of a number of LSI or VLSI circuits, the circuits are mounted in the receptacles on an appropriate burn-in board designed to operate those particular circuits. That burn-in board is plugged into the tester, which is programmed to operate the desired burn-in test for the integrated circuit packages which are to undergo test.
The printed circuit burn-in board typically is mounted on a frame; and the board is moved toward the test fixture with the pin connectors aligned with the corresponding pin receptacles on the test fixture. Usually, the board is manually inserted into the test fixture; so that all of the pin connectors are seated firmly into the receptacles on the test fixture. Each pin makes a friction fit engagement into the receptacle into which it is placed, to cause good electrical interconnection to take place between the tester receptacles and the pins connected to the printed circuit wiring on the printed circuit burn-in board.
In the past, when a different burn-in board is to be used with the test fixture, it is necessary to remove whichever burn-in board is in place by withdrawing it from the test fixture prior to insertion or interconnection of a new board. Because each of the pin connectors makes a friction fit with the receptacle into which it is inserted, some force is required to withdraw each pin from the receptacle. When only a small number of pins and a correspondingly small number of receptacles are involved, the force is not great; and pin separation readily, manually, can be accomplished. For the testing of a large number of LSI of VLSI integrated circuit packages, however, the number of pins inserted into the corresponding number of receptacles may extend into the hundreds. A typical commercial tester or test bench may include as many as four hundred sixteen pins and receptacles for interconnection. The result is a significant amount of withdrawal force is encountered when the burn-in test board is to be withdrawn or removed from the tester or test fixture.
In the past, it has been common for test engineers to carefully insert a screwdriver between the edge of the printed circuit burn-in board and the front of the tester to pry the burn-in board away from the tester. Usually, the screwdriver is inserted first on one side to move that side out a short distance, and then is moved to the opposite side of the test board to pry that side outwardly. This operation is alternated until the board is loose enough to be withdrawn by hand from the test fixture. A problem with the use of a screwdriver or similar tool to pry the burn-in board or other test board away from the test fixture is that the pressure of the screwdriver between the edge of the board and the front of the tester may cause damage to one or the other or both of these components. In addition, the prying, first of one side and then the other, causes a strain on the pin connectors, tending to bend them first in one direction or the other. A similar strain, which may result in misalignment of pin connectors, occurs when the test board is grasped on opposite sides and wiggled back-and-forth while at the same time applying withdrawing pressure to it.
If a pin connector is bent or misaligned, the next time the burn-in board is used, the misaligned pin may prevent insertion of the board into the test fixture; or the pin may require repair or replacement. The pin connectors have a relatively small diameter, and are somewhat fragile; so that bending or misalignment of the pins can occur when withdrawal of the burn-in board or other test board is effected using these techniques.
It is desirable to provide a device for extracting burn-in boards and other test boards, having large numbers of pin connectors in them, from a test fixture in a simple and effective manner, and which overcomes the disadvantages noted above.